The present invention relates to a heat exchanger core comprising a fluid passage member within which a fluid flows and outside of which another fluid flows and fin members formed thereon for promoting heat exchange between the two fluids, and more particularly to a heat exchanger core whose fluid passage member is made of an aluminum base alloy and whose fin members also serve as sacrificial anodes for protecting the fluid passage member from corrosion, when the heat exchanger core is used in the heat exchangers for condensers of car coolers or for radiators of cars.
A conventional heat exchanger for use in air-cooled heat exchangers, which is made of an aluminum base alloy and is assembled by brazing, comprises a fluid passage member for allowing a heat exchange medium, such as cooling medium or cooling water, to pass therethrough, and fin members disposed on the air-cooled side. In the heat exchanger, either the fluid passage member or the cooling fin members or both are prepared from brazing sheets comprising a layered member consisting of a core metal layer made of aluminum or a corrosion-resistant aluminum alloy, and a cleaning metal layer made of an Al-Si base alloy or an Al-Si-Mg base alloy, and these members are joined to each other by brazing.
However, when the heat exchanger is exposed to a severe corrosive atmosphere, considerable corrosion takes place in the air-cooled side of the heat exchanger and the fluid may leak from the fluid passage member. Therefore, the applications of such an air-cooled heat exchanger are severely limited. More specifically, in the conventional heat exchanger as shown in FIG. 1, a soldered fillet portion 2 between a fin member 1 and a fluid passage member 3 becomes a cathode, while the fluid passage member 3 itself becomes an anode, and a corrosion-current flows in the direction of the arrow from the fluid passage member 3 to the soldered fillet portion 2, so that pitting corrosion 4 occurs in the fluid passage member 3.